Capillary Biomedical Inc. is developing an infusion set (catheter/cannula/inserter) for the treatment of diabetes mellitus with continuous subcutaneous insulin infusion (CSII). The Capillary infusion cannula has been reinvented to include kink-resistance (an internal reinforcing coil), multiple outlet ports, an `effortless' automatic inserter and other performance- improving design elements. This combination of features will remove barriers to CSII therapy by increasing the infusion set replacement interval beyond the current 2 to 3-day standard. It will also substantially reduce the incidence of very common ? and frustrating ? failure modes that impact the health of diabetic persons, including: infusion set failure upon insertion, blocked insulin delivery due to kinking or occlusion, and infusion site reactions. This NIH phase 2 grant proposal addresses exploratory research objectives to study how the novel design of the Capillary infusion set reduces the failure rate and why it may be safe to extend continuous use of one Capillary infusion set for up to 7-days. This project consists of extensive in-vitro and in-vivo testing to ensure safety and reliability with the objectives of: 1. Fabricating Coil-Reinforced Soft Polymer CSII Sets The Capillary CSII Set design and pilot scale production process will be finalized to produce a minimum of 300 completed infusion sets suitable for human use. 2. Verifying Insulin Compatibility Over 14-Day Duration We will demonstrate the compatibility of our infusion set in non-clinical testing with Humalog (Insulin Lispro, Lilly) and Novolog (Insulin Aspart, Novo) to prepare for the human trial. 3. Clinical Trial to Assess the Capillary Infusion Set Performance in Humans A twenty-five-adult patient phase 1b inpatient hyperinsulinemia/euglycemia study in type-1 diabetics will be conducted in a randomized sequence, cross-over design to explore bioavailability and dose-response profiles of commercially available rapid-acting insulin when delivered using a CSII pump plus investigational Capillary catheter vs a commercially available Teflon catheter for 7 days. The proposed primary endpoint is insulin bioavailability (AUC 0 ?) on the day of insertion.